1. Field of the Invention
This invention relates to printing presses, to web-fed printing presses, and to means in such machines for threading a continuous web of paper or like printable material along any desired path through the printing and other processing stations of the machine preparatory to printing on the web. More particularly, the invention deals with such web-threading means equipped with self-cleaning facilities.
2. Description of the Prior Art
Large printing presses, those having a plurality of printing stations and post-printing processing stations for newspaper production, for instance, are usually furnished with a set of alternative web guideways providing for as many different paths along which the web may be threaded for specific printing assignments. Each web guideway is defined by a pair of spaced guide rails on each side of the web path. The web being threaded has its leading end pasted to a pair of web leaders of a plastic or like flexible material, which are slidably received one between each pair of spaced guide rails.
Each pair of guide rails are not continuous but are divided into sections, each less in length than the web leaders, which are longitudinally spaced one from another to accommodate pairs of opposed drive rollers. Frictionally engaged between each pair of drive rollers, the web leaders travel down a chosen guideway to lead the web, being unwound from its roll in the supply station, along the guideway.
One of the problems with such web-threading means has been how to clean the pairs of spaced guide rails and of drive rollers to assure smooth travel of the web leaders. The guide rails and drive rollers are very susceptible to the accumulation of solids, especially in the neighborhoods of the printing rollers, due to the higher concentrations there of ink mist intermingled with paper fibers and particles.
The staining of the drive rollers with ink mist is particularly objectionable because the web leaders are easy to slip over the stained drive rollers. The possible results of such web leader slippage have been the slackening of the web, the entanglement of the slackened web with the neighboring parts, and the ultimate breakage of the web. Manual cleaning of the guide rails and drive rollers is of course very troublesome and time-consuming, adding much to the downtime of the machine.
Japanese Unexamined Utility Model Publication No. 7-2051 teaches how to clean the guide rails. It suggests use of what might be described as brushes, which are movable in grooves cut in the guide rails. Driven by the noted pairs of drive rollers, the brushes travel along the guide rails to brush away the dirt and dust.
Hygienically, this method of guide rail cleaning is preferable to the more conventional method of blasting the dust away by forced drafts of air, by virtue of less amounts of dust particles scattered into the plant atmosphere. The brushing go method has proved unsatisfactory, however, as it still scatters the dust into the air, though to lesser extent, and unnecessarily stains the neighboring parts of the machine.
Another objection to the brushing method is that the brushes must travel between the pairs of drive rollers. Squeezed hard by each pair of drive rollers, the brushes have been easy to wear out, very quickly becoming useless, incapable of scrubbing the groove bottoms.
It is among the objects of this invention to clean the guide rails and drive rollers of web-threading apparatus concurrently with web-threading, in such a manner that pollution of the plant atmosphere with dust particles is totally averted.
Another object of the invention is to clean the desired parts of the web-threading apparatus far more thoroughly, and far more effectively, than heretofore.
A further object of the invention is to preclude the slipping of the web leaders over the drive rollers, and the consequent slacking of the web, in the act of concurrent web threading and guide rail cleaning.
A still further object of the invention is to make the self-cleaning web-threading apparatus far more durable and trouble-free than heretofore.
Briefly, the present invention may be summarized as a self-cleaning web-threading apparatus for a web-fed printing press wherein a web of paper or like printable material is threaded through the press along any of a set of alternative web guideways for each specific printing job. The web-threading apparatus comprises guide rail means defining a web guideway along which a web is to be threaded by a web leader traveling in sliding engagement with the guide rail means. The web leader is fabricated at least in part from a detergent-absorbing material for sliding contact with the guide rail means. Disposed in any selected position or positions on the web guideway, detergent supply means supply, as by roller-coating or spraying, a detergent to the web leader traveling along the web guideway, thereby impregnating the web leader with the detergent.
Thus the guide rail means are cleaned by the detergent-impregnated web leader as the latter travels in sliding contact therewith. The guide rail cleaning by the web leader can be either concurrent with, or preliminary to, the threading of the web along the guideway.
In practice the web leader may take the form of an elongate, flexible baseplate covered on both sides with woven fabric. Experiment has proved that ink-stained guide rails can be cleaned far more efficaciously by detergent-impregnated fabric than by air-blasting or brushing. The detergent has also proved to serve the additional purpose of lubricating the web leader, enabling the same to travel over the guide rails with a minimum of friction, both when the guide rails are dust-laden and after they have been cleaned.
Threaded by the detergent-impregnated, smoothly traveling web leader, either after, or at the same time with, guide rail cleaning, the web of paper is not to develop slacks and so not to get caught by the neighboring machine parts. Web threading has thus become possible in shorter periods of time than heretofore.
The fabric covering the web leader, or any other detergent-absorbent material adoptable in its stead according to the invention, is not to become easily useless by being repeatedly caught by the drive rollers feeding the web leader along the web guideway. When itself stained, moreover, it may be detached from the web leader and cleaned for reuse.
The above and other objects, features and advantages of this invention will become more apparent, and the invention itself will best be understood, from a study of the following description and appended claims, with reference had to the attached drawings showing some preferred embodiments of the invention.